A magnetic tape has been known as an inexpensive mass storage medium. In some of a linear type magnetic tape, a plurality of tracks are formed, data is written in a certain track in a forward direction from the beginning of the track, and, when the writing is completed up to the end of the track, data is written in another track in a backward direction. As a standard of this type of magnetic tape, a Linear Tape-Open (LTO) Ultrium has been in wide use.
As an example of techniques related to writing in a magnetic tape, there has been proposed a technique for calculating a data length up to a reversal position on the basis of the entire amount of data to be written in the magnetic tape, writing the data up to the calculated reversal position in a forward direction, and then writing the remaining data in a backward direction.
A related technique is disclosed in, for example, Japanese Laid-Open Patent Publication No. 08-045182.
When the data is written up to the reversal position and then the remaining data is written in a backward direction as in the above-described technique, a direction reversal operation for backward reading is performed at the reversal position by a tape drive to read the written data. Such a direction reversal operation takes a relatively long time such as, for example, 2 seconds. Therefore, when a direction reversal operation occurs in the middle of reading data from the magnetic tape, there is a problem of taking a relatively long time to read the data.